Fixed Deposit interst income - GST Applicable

A user is seeking clarification on whether Goods and Services Tax (GST) is applicable to interest earned on Fixed Deposits (FDs) held by their firm. During an audit for FY 2020-21, the auditor suggested that FD interest is subject to GST. The user is asking for guidance on this matter, particularly how to account for past interest if GST is indeed applicable. Another user has pointed out that, as per Notification No. 12/2017, interest on deposits is generally exempted from GST.